Method of making bronze backed, cast babbitt lined bearings



United States Patent 2 O METHOD OF MAKING BRONZE BACKED, CAST-BABBITTLINED BEARINGSuw Jame Bi Mo hler, ew ca' fl; "r5 Assigns?tjohn's'aii Bronze CompanyyNew'castle, a fa corporation of Drawing.-Appli catibnApi-il1 2', 19,54; Y; r Nq-msss it This invention relatesto a method ofrn'aking composite bearings comprising a bronze backingand arcast babbitt lining with' improved bond'life. .A

"T here are many bronze 'backed,'cast babbitt lined bearings inservicestoday-with unsatisfactory bearing life. Complaintsare'z-numerous that 'the bond between the: cast babbitfimetal liningandthe bronze. backing isi unsatisa factory. ,4

Bronze backedycast babbitt lined,- railroad journal bean ings are nowmanufacturedby:.the=followingmethodi 5 proper size, thebackingtispaintedwith an inorganic stopofl materialto prevent tinning of thisarea,- thes'rnachiried surface is wiped with zinc chloride flumandithebronze backing is allowed to float on a lead-tin bath containing 70%leadtand 30% tin until the backing is ,tinned":and preheated. alloys maybet650 "v F. andthenbackingmayibe: subjected tothepreheat tinning alloyfor say 1 10 minutes Jl-"he backing having acoatin'gofthe"preheatgtihhirigf Loy thereonis removed from the tinningb'athan'dis clamped in a'rack. Molten Babbitt metal at a temperature oftay 740 F. is t'hen'cast' against the coatedbacking mediately"thereafterw ater'iis p'ra' ea against Efllflibatak or the backing to cooljitquickly.f The bearin he nlre- This ni'ethodrequire accurate control f'thv steps 'in order toiproduce a satisfactory bo' Bab'bitt'metal liningand "bronze back ng; ad n n l P 1, tinning alloy, tlie t acking n thpreheat nning allolyg th'e temper I "when .the nioltenB abbitt metallining is poured onto he backing, the temperature of'theBabbittmetal.when is'poiiried onto the backing and the'tirne" interval betwe 'ing andspraying the backing with water Although there is some latitude inlthetime jand' t'eirnperatures 'mplo'yedin the various steps, they must :be'controlled w hin; rather accurate limits in order to: obtainsatisfactory bonding (a; Babbitt m an ate, t "br nzsgb k y i lt ltemperatures'a're toolow' onthe he i'n'g times 1 atisfa t r r s v will int W1 i, p'eratures are too high or the \heatingtirnes are too long, thebond between the ti lri Q jtaining Babbitt'rnetal and {the bronzebackingwill dete' 'orate. This bond deterioration H v psu essjfditemperature" 'of the h g n aytoccurinmaking thebearing or inl tlie usejof the ar- The. temperature of .the ,preheataftinning 'irig.z-1 -It willbe understood, using bearing 2,712,166 Patented July 5, 1 955 may, reacha? temperature of 200,- 300-,', ;400-. degrees E.-;or higher ;and atthese temperatures ;bond deterioration; may occur.- Furthermore,= {thebearingsornetimes ,is annealed in order to. reduce the brittleness ofthGwBtlbbltLIl'ltllf lin irig 1 so :as 51:0 prevent cracking ;thereof1,7durin g, machiningz This-also tends;to=cause';the; bondtodeteriorate; 1

The? .-following& data illustrate the; effect producedon the-bondlbyt:heating bronzebacked, cast babbitt; lined bear,- ings at 300 F. for thetime indicated. In making the bearings,-. the temperature: ,of ,1 the;preheat tinn ing-f ;alloy bath was 65 0? F; and the'i temperature 1 of-.the Babbitt metalvwasj750 ;F.1when1cast'-' tonto the;bro'nze backing.The bronzelcompositionsemployediwere: w'.

Backing .t Bronze.

l3 earing Number iitiw'asfound that' tin base babbitt suchsas:babbrtt 2almost :invariably had a brittle bond. on, castingithat could not :beiinprovedi-by annealing andathat deteriorated on heating. This isthought to be due to structuralchange's inzathe babbitt rather ithan dueto JbOHd'T dCtGIiOIatiGHE Fronrflable Litcan be seen that in the.casetof thelead base babbitts, even though:thet-bondtisvgood inthe'ascastgconditi'on' ofl the bearing, the tbond -life i's':short' when thebearing-is 'heatedx The bonds in=bearing-Nos.-;2 .an'dv3 deteriorated:at 4 r 'h'ours'iiheating; that kof beaiiiag'sltlol .55 at l6-rzhtmrs:heating and that'iof bearing:v N0." .66 hours": heating; "all wat a rternperatur'eziof 3009 :E.3.-"Other tests of bearings heated": tolow'er:ftemperatures 'zshoived lohgeribohd life: but even at; temperaturesbelow 200? the bond life was only a few 1 hundred hours whereasv-forsatisfactory" bond life ax-bearingtin many. instances :-is required torun 'rnany hundreds of hours" atv these; temperatures-. As previously.stated; bond deterioration nlayx b'e caused byithe heati developed:inanaking: the bearing; by

hEtpuSEdgin annealingdti-orby that. developed in -us'e,-0.f

the beari-ngior .by-,a=,combinatiQn-:ot all of-thesefaetors.

1; n. ha eo d t t in n ma am ac orda sezwi h he me ho sc bed y, set in mtent n-ssntainipg cking deter r41 k.) overcome by the use of anelectrodeposited barrier layer of metal such as nickel, cobalt, or ironbetween the bronze backing and the cast tin-containing babbitt. I canuse as the barrier layer any metal or alloy that will prevent or greatlyinhibit diffusion of tin from the Babbitt meta lining into the bronzebacking, that can be bonded to the bronze backing and on which thetin-containing, lead base babbitt can be bonded by casting. By employingthe layer of barrier metal, casting of the tin-containing Babbitt alloycan be done at higher temperatures to assure that bonding will takeplace by exceeding the minimum thermal conditions usually required,without causing bond deterioration.

I have found that a very thin layer of nickel will cause the bond lifeof a cast lead base babbitt on bronze hearing to be suiliciently longthat the hearing will not fail due to this cause. A nickel barrier layer01 mil thick and even. less will increase the bond life beyond 2000hours when heated at 300 F. or beyond 400 hours when heated at 400 F.Tests for longer times at these temperatures 11.

were carried out and it was found by chisel tests that the bond wasstill good but these times and temperatures are considered suificientlylong to show that the bond life is longer than the normal hearing life.

A nickel barrier layer 0.025 mil thick showed bond eterioration of leadbase cast babbitt on bronze after 100 hours at 400 F. For thicknesses of0.05 to 1.0 mil, the bond was good after heating for 400 hours at 400 F.A thickness of 0.1 to 0.2 mil is considered to be practical, althoughthicker or thinner nickel barrier layers may be used.

The nickel plating may be accomplished in a known manner. Asillustrative of a satisfactory method, the bronze backing is degreasedwith trichlorethylene, subjected to anodic electrolytic cleaning in asolution of s sodium hydroxide, sodium cyanide and Rochelle salts,

pickled in a solution of hydrochloric and tartaric acid and V nickelplated in a bath containing:

Nickel sulfate g./l 275 Nickel chloride g./l

Boric acid g./l 40 pH 3 casting method as follows, compositions A and Bbeing typical examples of bro'nzes and compositions 1 and 3 beingtypical examples of lead base, tin-containing babbitts.

The rough bronze casting is machined on the inside, outside and ends toproduce a cylindrical shape. inside of the cylinder is electroplatedwith a barrier layer of nickel, cobalt or iron, preferably nickel, thebarrier layer being between 0.05 and 1.0 mil thick, preferably between0.1 and 0.2 mil thick. The outside or" the backing may be coated with aninorganic stop-off to prevent tinning in selected areas. The bronzebacking is dipped in or wiped with zinc chloride solution for fluxingpurposes and then immersed in a molten tinning bath to preheat thebacking and apply a coating of tinning metal to the inside of thecylindrical backing. The tinning metal may be a lead-tin ping thespinning, the bearing is removed from the spinning machine and thebabbitt lining is machined .into cylindrical bearings or the cylindersmay be split to produce half-cylindrical bearings. Also, the bearingsmay be produced with flanges or in other special shapes that can be madefrom a cylindrical, or modified cylindrical, casting. The temperature ofthe molten Babbitt metal at the time of casting may be from 500 to 1200F., usually between 600 and 1000 F., the preferred range of temperaturebeing between 650 and 800 F. The temperature range of the tiuning bathand the molten babbitt may vary considerably depending upon the size ofthe backing. If the backing has a high heat content due to its mass, thebacking may be tinned in a tinning bath at low temperature and/or thebabbitt may be cast at a low temperature. On the other hand, if thebacking has a thin wall and low heat content, it may be necessary to tinin a tinning bath at high temperature and/or to cast the babbitt at ahigh temperature to insure that the babbitt will be molten for asufiicient time after pouring it onto the backing to conform to thedesired shape during spinning and for a suflicient time to create abond. The backing is usually held in the preheating and tinning bath for15 to 60 seconds. After casting the Babbitt metal in the backing, thebacking is usually allowed to spin for 2 to 10 seconds before quenchingand the quench is usually applied for 15 seconds to 2 minutes, althoughthis usually is not timed but is stopped when steam no longer rises fromthe backing.

Another method by which bearing shells may be made according to myinvention is by static casting the Babbitt metal between a cylindricalbronze shell and a removable carbon core. Shells were cast by thismethod on nickel plated bronze using bronze composition B and babbittcomposition 3 as follows.

The bronze casting was bored on the inside and anodically etched for 1minute at 6 volts in the following aqueous solution:

G./l. Sodium cyanide 40 Sodium hydroxide 40 Rochelle salts 20 The shellwas rinsed and then dipped in an aqueous solution consisting of a Percent by weight Hydrogen chloride 14 Tartaric acid 5 The shell was rinsedand immersed in a Watts type nickel plating bath and plated for 1 hourand 20 minutes at a current density of 15 amperes per square foot.Molten Babbitt metal was cast statically into the shell using a carboncore and the shell was allowed to cool naturally. Measurement of a crosssection under a microscope showed the nickel thickness to be 0.8 mil.After machining away a part of the babbitt lining, the shells wereheated to determine the hot bond life. Some of the shells showed goodbond life by chisel test after heating for 2000 hours at 300 F. Othershells showed good bond life after heating for 1150 hours at 400 35.These values are far in excess oi what would normally be required of anengine bearing under operating conditions in an engine.

The invention is not limited to the preferred embodiment but may beotherwise embodied or practiced within the scope of the followingclaims.

I claim:

1. The method of making bronze backed, cast babbitt lined bearings,which comprises electrodepositing a thin barrier layer of metal of thegroup consisting of nickel, cobalt and iron on a bronze backing, andcasting molten lead base, tin-containing Babbitt metal on said barrierlayer to form a bearing lining.

2. A method according to claim 1, wherein the barrier layer is 0.05 to1.0 mil thick.

3. The method of making bronze backed, cast babbitt lined bearings,which comprises electrodepositing a thin barrier layer of metal of thegroup consisting of nickel,

5 cobalt and iron on a bronze backing, preheating the backing coatedwith barrier metal in a molten tinning bath, removing the backing coatedwith tinning metal from the tinning bath and casting molten lead base,tincontaining Babbitt metal on said coating of tinning metal to form abearing lining.

4. The method of making bronze backed, cast babbitt lined bearings,which comprises electrodepositing a barrier layer of metal of the groupconsisting of nickel, cobalt and iron having a thickness of 0.05 to 1.0mil on a bronze backing, preheating the coated backing in a moltentinning bath having a temperature between 500 and 800 F., removing thebacking coated with tinning metal from the tinning bath and castingmolten lead base, tincontaining Babbitt metal having a temperaturebetween 500 and 1200 F. on said coating of tinning metal to form abearing lining.

5. A method according to claim 4, wherein the molten lead base,tin-containing Babbitt metal is at a temperature between 600 and 1000"F. when cast on said coating of tinning metal on said backing.

6. A method according to claim 4, wherein the molten lead base,tin-containing Babbitt metal is at a temperature between 650 and 800 F.when cast on said coating of tinning metal on said backing.

No references cited.

1. THE METHOD OF MAKING BRONZE BACKED, CAST BABBITT LINED BEARINGS,WHICH COMPRISES ELECTRODEPOSITING A THIN BARRIER LAYER OF METAL OF THEGROUP CONSISTING OF NICKEL, COBALT AND IRON ON A BRONZE BACKING, ANDCASTING MOLTEN LEAD BASE, TIN-CONTAINING BABBITT METAL ON SAID BARRIERLAYER TO FORM A BEARING LINING.